A probe to determine the rate of non-dipping blood pressure (<10% lowering of blood pressure from awake to asleep) in black adolescents with normal blood pressure as a potential marker for individuals prone to the development of high blood pressure with no discoverable organic cause or cardiovascular complications. In previous studies, it has been shown that there is a 30% prevalence rate for non-dipping blood pressure status in a small sample of 55 normal adolescents. It was also discovered that a greater percentage of non-dippers were salt-sensitive, showing increased pressure from salt intake. Also, these salt-sensitive individuals reversed their non-dipping status in response to increased potassium in the diet. The objectives of this study are a) to obtain data on the prevalence of non-dipping blood pressure status in a larger representative sample of black adolescents with normal blood pressure, and b) to examine salt and potassium and catecholamine excretion as potential correlates of non-dipping status in this black adolescent population. Ambulatory heart rate responses will be estimated. Ambulatory blood pressure non-dipping status is a risk factor for end-organ disease, stroke, and left ventricular enlargement. Research has discovered that black adults and children have higher nighttime blood pressure than whites, and to date, little is known why. A total of 150 black adolescents will be randomly recruited from the Richmond area over a period of a year. Only healthy adolescents will be enrolled. They will be black males and females, not greater than 25% over ideal body weight for height, have normal blood pressure, no chronic illnesses, ages 13-15 years, no history or symptoms of cardiovascular disease or renal impairment, on no medications, not pregnant or taking oral contraceptives. Parents will accompany the teenagers to the General Clinical Research Center to sign a consent form. On test days, subjects will be asked to refrain from smoking and drinking alcoholic or caffeinated beverages. A medical history will be assessed, blood pressure will be taken, family histories discussed, and urine samples, weight, height, and body mass will be measured. Instructions will be gives as to how all the procedures will be done. A questionnaire regarding family, neighborhood, and adolescent identity issues will be filled out. A 24 hour blood pressure monitor will be placed on the subject's arm and will automatically measure pressure every 15 minutes. The device will be removed the next day. Instructions will be given on how to collect two 24 hour urine samples.